Circle button and blacked screen!

[Vrbuxton1]

Hello all. Sorry if this is a simple fix, but I've just switched from iOS to android and I'm having a mare.

I have a circle button which has just popped up on my screen and floats above everything. I have no floating menu option (I have a P20 Pro) and I am using Nova launcher. How do I get rid of it?!

My second issue is that my whole screen has changed to darker/reverse colours without me doing anything. None of my dark modes are activated.

Any help appreciared!

 

[SpookDroid]

Have you checked the Accessibility settings on your phone? There are a few options there that can trigger those, especially the inverted colors for enhanced visualization. If you tap the floating button, does it do anything or do any options pop up? If so, when you 'open' it, does it show a menu button that might have settings? Or tap-and-hold it to see if an 'X' pops up (that usually clears these from the screen).